Kevin Zhang created FLINK-14539:
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Summary: Unique key metadata should be ketp when using concat or
concat_ws in some cases
Key: FLINK-14539
URL: https://issues.apache.org/jira/browse/FLINK-14539
Project: Flink
Issue Type: Bug
Components: Table SQL / Planner
Affects Versions: 1.9.1, 1.9.0
Reporter: Kevin Zhang
Currently unique key metadata of a project relnode are only kept in the
following three situations:
# project the child unique keys while not changing them
# cast the child unique key when ignoring nulls and the original type of the
field and cast type are the same
# rename the child unique keys
Besides these situations, concat and concat_ws should also keep the metadata if
they won't break the uniqueness of the child unique keys, i.e. each operands is
in one of the above situations, and the operands include all the child unique
keys.
Say the f0 and f1the child are the unique keys of the child node, the following
sqls should keep the unique key metadata
{code:sql}
select concat(f0, f1)
-- the type of f0 and f1 are both varchar originally and ignore nulls
select concat(cast(f0 as varchar), f1)
select cast(concat(f0, f1) as varchar)
{code}
while the following sqls should discard the unique key metadata
{code:sql}
-- the type of f0 and f1 are both varchar originally
select concat(cast(f0 as bigint), f1)
select cast(concat(f0, f1) as bigint)
{code}
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